How much money should you spend at the mall?

you should bring about $20 and every time you want something think about it. about will i use it? do i need it? if its a t-shirt think is it appropriate for my age? or will i grow out of that style quickly? if you are 10 don't walk around the shopping mall wearing a shirt that is imodest or all your back or other place that shouldn't be seen is showing. :)